This invention relates to boxes having a hinge connecting the box lid to the box body, and particularly to maintaining closed the lid of a hinged lid box having rounded corners for containing smoking articles such as cigarettes.
One type of package in which cigarettes are sold is a hard paperboard box having a hinged lid. A hard paperboard innerframe is secured to the front of the box body and extends out the body. The cigarettes are bundled in a foil liner inside the box body and are at least partially surrounded by the innerframe. The box lid fits over the innerframe and the cigarettes. The innerframe provides a frictional engagement surface to retain the lid in the closed position and protects the cigarettes that extend above the box body from damage.
Conventional hinged lid boxes have a flat panel at the lower edge of the front panel that is folded 180 degrees and secured to the inside surface of the lid front panel. This flap extends substantially the width of the lid front panel and is typically less than one half of the height of the lid front panel. The flap increases the rigidity of the lid front panel and provides a smooth, non-cut lower edge.
Hinged top boxes are made with substantially right angle corners or with rounded corners. It is important for each style of box to maintain the box lid closed so that the box will not open inadvertently and spill its contents, for example, smoking articles or loose particles of smoking material such as tobacco. The box lid closure should also be aesthetically pleasing to enhance the general appearance and consumer acceptance of the box.
One known technique for maintaining right angle corner boxes closed includes providing the innerframe with u-shaped slits or retention cuts at the innerframe corners so that when the innerframe is folded, u-shaped tabs extend outwardly from each corner in the plane of the innerframe front panel. Thus, when the lid is closed, the tabs engage the interior side panels of the rectangular lid, pressing the lid sides apart and holding the lid tightly against the innerframe.
U.S. Pat. No. 4,753,383 refers to applying the innerframe corner tab technique to boxes having rounded corners. However, the tabs formed on the innerframe corners do not engage adequately the lid corners to press the lid sides apart or to hold the lid closed. Rather, the tabs are either sheared off or damaged by the bottom edge of the lid as the lid is closed, or urged to follow the curvature of the corners by the forces acting on the tabs from the lid corners and thus pushed back into the slits from which the tabs were cut. The result in either case is that forces exerted between the lid and the innerframe are insufficient to hold the lid sufficiently closed, notwithstanding that the lid may be mostly closed. The partial opening is unacceptable in a commercial product because it permits inadvertent opening of the box, leakage of the contents, and, in particular, results in an package that is unattractive and unacceptable to the consumer.
U.S. Pat. No. 4,753,383 also refers to maintaining a lid closed by cutting the front panel of the innerframe to form an anchoring tab. The anchoring tab is folded back 180 degrees onto the innerframe front panel so that the bottom edge of the anchoring tab will engage the top surface of a reinforcing strip that is secured to the inside surface of the lower edge of the lid front panel. When the lid is closed, the anchoring tab and the reinforcing strip are in end to end abutment in the same plane. This technique has not appeared in any commercial product. It is believed to be impractical due to the close tolerances required and the difficulty of maintaining the end to end abutment following repeated disengagement of the anchoring tab and the lid and the undesirable presence of the anchoring tab on the innerframe.
Accordingly, there is a continuing need for apparatus and methods for closing box lids for rounded corner hinged lid boxes that are easy to manufacture, aesthetically suitable, and maintain the box fully closed even after repeated use.